i have a few links i've saved over the years to sites that are still up at the moment where people have done some work with biodigesters. this is one that is pretty neat i think and is worth adding to the mix here, if that is ok.

I'm in Costa Rica right now, returning to Alaska in April. There are a lot of these digesters around, but I've seen only one that is producing burnable gas. I think there is huge demand/opportunity in teaching/learning how to start them and keep them running.